WO2014087994A1 - ディスカバリ方法、光通信方法、及び光通信システム - Google Patents
ディスカバリ方法、光通信方法、及び光通信システム Download PDFInfo
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- WO2014087994A1 WO2014087994A1 PCT/JP2013/082460 JP2013082460W WO2014087994A1 WO 2014087994 A1 WO2014087994 A1 WO 2014087994A1 JP 2013082460 W JP2013082460 W JP 2013082460W WO 2014087994 A1 WO2014087994 A1 WO 2014087994A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
- H04J14/0241—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
- H04J14/0242—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON
- H04J14/0245—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for downstream transmission, e.g. optical line terminal [OLT] to ONU
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/27—Arrangements for networking
- H04B10/272—Star-type networks or tree-type networks
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
- H04J14/0241—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
- H04J14/0242—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON
- H04J14/0245—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for downstream transmission, e.g. optical line terminal [OLT] to ONU
- H04J14/0246—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for downstream transmission, e.g. optical line terminal [OLT] to ONU using one wavelength per ONU
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
- H04J14/0241—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
- H04J14/0242—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON
- H04J14/0249—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for upstream transmission, e.g. ONU-to-OLT or ONU-to-ONU
- H04J14/025—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for upstream transmission, e.g. ONU-to-OLT or ONU-to-ONU using one wavelength per ONU, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/08—Time-division multiplex systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/06—Synchronising arrangements
- H04J3/0635—Clock or time synchronisation in a network
- H04J3/0682—Clock or time synchronisation in a network by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
- H04J14/0241—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
- H04J14/0242—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON
- H04J2014/0253—Allocation of downstream wavelengths for upstream transmission
Definitions
- the present invention relates to a discovery method, an optical communication method, and an optical communication system in a wavelength tunable WDM / TDM-PON.
- FTTH Fiber To The Home
- ONU Optical Network Unit
- TDM Time Division Multiplexing
- OSU Optical Subscriber Unit
- PON Passive Optical Network
- the burst transmitter in each ONU 200 transmits signal light within the allowable transmission time notified based on the dynamic bandwidth allocation calculation in the OSU 51, and the intensity from each ONU 200
- the burst receiver in the OSU 51 receives the signal light obtained by multiplexing the signal lights having different phases on the time axis.
- the current main systems are GE-PON (Gigabit Ethernet (registered trademark) PON) and G-PON (Gigabit-capable PON), which have a transmission speed of gigabit. Due to the appearance of applications for uploading / downloading, etc., there is a demand for further increasing the capacity of the PON system.
- FIG. 2 is an example of WDM / TDM-PON in which WDM technology is combined with TDM-PON.
- Each ONU 200a is assigned with a downstream wavelength and an upstream wavelength, and the time overlap of signals between the ONUs 200a is allowed up to the number M of OSUs 51 in the parent node 100a (M is an integer of 2 or more). Therefore, the system bandwidth can be expanded without increasing the line rate per wavelength by adding the OSU 51.
- Each ONU 200a assigned the same upstream wavelength is logically connected to the same OSU 51 and shares a band.
- the wavelength allocated to each ONU 200a is fixed, the logical connection between each ONU 200a and the OSU 51 is unchanged, and the bandwidth cannot be shared between the ONUs 200a connected to different OSUs 51, and the bandwidth fairness is not ensured. .
- Non-Patent Document 1 proposes a wavelength tunable WDM / TDM-PON in which an ONU has a wavelength tunable function as shown in FIG.
- the OSU that is logically connected in units of ONUs can be changed by changing the wavelength allocated to the ONU, and the system band can be shared among all the ONUs. Therefore, the wavelength variable burst transmitter in each ONU transmits the signal light within the notified transmission allowable time at the transmission wavelength notified based on the dynamic allocation calculation in the OSU, so that all the ONUs Bandwidth fairness can be ensured.
- each ONU uses an identifier such as LLID (Logical Link ID) to determine whether the received frame is addressed to itself. The frame is selected.
- LLID Logical Link ID
- the ONU transmits a transmission frame in which an identifier assigned to itself is embedded, and the OSU determines which ONU the frame is transmitted from, based on the identifier in the reception frame.
- the OSU manages the identifiers of all ONUs under its control, and assigns identifiers to newly connected ONUs so that duplication with existing ONUs does not occur through the discovery process.
- the frame round trip time (RTT) between the OSU and the ONU is also measured, and the OSU stores the RTT information with all the ONUs under its control.
- the OSU determines the allowable transmission time of the upstream signal light from each ONU in consideration of the RTT, thereby avoiding the collision of the upstream signal light (see, for example, Non-Patent Document 2).
- the wavelength variable WDM / TDM-PON similarly to the TDM-PON, it is necessary for each OSU to grasp the identifiers and RTT information of all ONUs logically connected to itself. Further, the ONU needs to recognize the identifier assigned to itself.
- the OSU that is logically connected in units of ONUs is changed by changing the wavelength assigned to the ONU. It is necessary to redo the discovery process every time. However, since the transmission of the data signal is not permitted during the discovery process, the bandwidth utilization efficiency decreases.
- an identifier assigned through the discovery process is fixedly assigned even after the assigned wavelength is changed, and a management table as shown in FIG. 16 describing information for all ONUs together with the measured RTT is provided between OSUs.
- a management table as shown in FIG. 16 describing information for all ONUs together with the measured RTT is provided between OSUs.
- the transmission timing of the upstream signal light is determined in consideration of the RTT, there is a possibility that the upstream signal light collides due to an RTT error.
- it is possible to prevent collision of signal light by providing a guard interval having a sufficient time between the upstream signal lights, but there is a problem that band utilization efficiency is lowered.
- the present invention reduces the error of RTT when the identifier is fixed even after the change of the assigned wavelength in the wavelength tunable WDM / TDM-PON, and prevents a decrease in bandwidth utilization efficiency. It is an object to provide a discovery method, an optical communication method, and an optical communication system.
- the present invention provides a table in which the RTT of the frame between each identifier is recorded for all combinations of assigned wavelengths. It was decided to create it through the discovery process.
- the discovery method according to the present invention is a wavelength-variable WDM / TDM-PON (WDM: Wavelength Division Multiplexing, TDM: Time Division Multiplexing) in which a parent node and a plurality of child nodes are connected by an optical fiber transmission line.
- PON Passive Optical Network
- Ranging is performed to calculate RTTs for all combinations of the downstream wavelength of the downstream signal and the upstream wavelength of the upstream signal from the child node to the parent node, and RTTs for all the combinations calculated by the ranging are stored. It is characterized by.
- the discovery method Based on the wavelength dependence of the search signal wavelength, the response signal wavelength, the RTT obtained by the discovery process, and the refractive index of the known optical fiber transmission line, the discovery method The combination RTT is calculated and stored in the table. For this reason, when the wavelength allocated to the child node is changed, an accurate transmission timing can be determined by referring to the corresponding RTT in the table. For this reason, the time of the guard interval between upstream signal lights can be reduced, and band utilization efficiency can be improved.
- the present invention provides a discovery method capable of reducing an RTT error and preventing a decrease in bandwidth utilization efficiency when an identifier is fixed even after an assigned wavelength is changed in a wavelength tunable WDM / TDM-PON. Can do.
- An optical communication method is an optical communication method in a wavelength tunable WDM / TDM-PON in which a parent node and a plurality of child nodes are connected by an optical fiber transmission line,
- the identifier assigned to the child node is unchanged when the wavelength is changed
- the table stores RTTs for all combinations of the downstream wavelength of the downstream signal from the parent node to the child node and the upstream wavelength of the upstream signal from the child node to the parent node; Referring to the table, RTT corresponding to a combination of a downstream wavelength and an upstream wavelength assigned to the child node is detected, an allowable transmission time of an upstream signal is determined in consideration of the RTT, and notified to the child node It is characterized by doing.
- This optical communication method uses a table storing RTTs of all combinations of downstream wavelengths and upstream wavelengths.
- RTTs of all combinations of downstream wavelengths and upstream wavelengths.
- the present invention provides an optical communication method capable of reducing an RTT error and preventing a decrease in bandwidth utilization efficiency when an identifier is fixed even after an assigned wavelength is changed in a wavelength tunable WDM / TDM-PON. be able to.
- the optical communication method according to the present invention is characterized in that RTTs in all the combinations are calculated by the ranging performed by the discovery method.
- the optical communication system transmits a downstream signal having wavelengths ⁇ D1 to ⁇ DM (M is an integer of 2 or more), and an upstream having wavelengths ⁇ U1 to ⁇ UN (N is an integer of 2 or more).
- M is an integer of 2 or more
- N is an integer of 2 or more
- a plurality of child nodes that receive a downstream signal having a downstream wavelength and send an upstream signal at the allocated upstream wavelength;
- An optical communication system comprising:
- the parent node is A table storing RTTs for all combinations of downstream wavelengths and upstream wavelengths for each identifier; Referring to the table, RTT corresponding to a combination of a downstream wavelength and an upstream wavelength assigned to the child node is detected, an allowable transmission time of an upstream signal is determined in consideration of the RTT, and notified to the child node A controller to It is characterized by having.
- This optical communication system includes a table that stores RTTs of all combinations of downstream wavelengths and upstream wavelengths.
- a table that stores RTTs of all combinations of downstream wavelengths and upstream wavelengths.
- the present invention provides an optical communication system capable of reducing RTT error and preventing reduction in bandwidth utilization efficiency when an identifier is fixed even after a change in allocated wavelength in a wavelength tunable WDM / TDM-PON. be able to.
- This optical communication system has the following configuration.
- the parent node is: A plurality of optical transceivers each set with a unique downstream wavelength and a unique upstream wavelength; Connected to each of the optical transceivers, wavelength-multiplexed downstream signals having different wavelengths from the optical transceiver and output to the optical fiber transmission line, branching the upstream signal from the optical fiber transmission line, Optical multiplexing / demultiplexing means coupled to the optical transceiver; Have The controller is At the time of discovery, the one optical transmitter / receiver transmits one downstream wavelength search signal, and the discovery method is performed using a response signal transmitted by any unregistered child node received by any of the optical transmitter / receivers. It is characterized by performing.
- the parent node is A plurality of optical transceivers capable of setting downstream wavelengths of wavelengths ⁇ D1 to ⁇ DM ;
- Each of the optical transceivers is connected via an optical transceiver side terminal, and the downstream signal from the optical transceiver is output from a different optical fiber transmission line side terminal according to the downstream wavelength and coupled to the optical fiber transmission line
- Have The controller is At the time of discovery, a plurality of the optical transceivers transmit a search signal of one downstream wavelength, and the discovery method is performed using a response signal transmitted by the unregistered child node received by any of the optical transceivers. It is characterized by performing.
- the parent node is A plurality of optical transceivers capable of setting at least one of the downstream wavelengths of wavelengths ⁇ D1 to ⁇ DM ; Connected to each of the optical transceivers, wavelength-multiplexed downstream signals having different wavelengths from the optical transceiver and output to the optical fiber transmission line, branching the upstream signal from the optical fiber transmission line, Optical multiplexing / demultiplexing means coupled to the optical transceiver; Have The controller is At the time of discovery, the search signal of a plurality of downstream wavelengths is transmitted using at least one of the optical transceivers, and the response signal transmitted by the unregistered child node received by any of the optical transceivers is used. A discovery method is executed.
- the parent node is: A plurality of optical transceivers capable of setting downstream wavelengths of wavelengths ⁇ D1 to ⁇ DM ; Each of the optical transceivers is connected via an optical transceiver side terminal, and the downstream signal from the optical transceiver is output from a different optical fiber transmission line side terminal according to the downstream wavelength and coupled to the optical fiber transmission line A wavelength routing means for outputting an upstream signal from the optical fiber transmission line input to the optical fiber transmission line side terminal from the optical transceiver side terminal different according to an upstream wavelength and coupling to the optical transceiver; Have The controller is At the time of discovery, one optical transceiver transmits a plurality of downstream wavelength search signals, and the discovery method is performed using a response signal transmitted by an unregistered child node received by any of the optical transceivers. It is characterized by performing.
- the present invention relates to a discovery method, an optical communication method, and an optical communication method capable of reducing an RTT error and preventing a decrease in bandwidth utilization efficiency when an identifier is fixed even after changing an allocated wavelength in a wavelength tunable WDM / TDM-PON, and An optical communication system can be provided.
- TDM-PON It is a figure explaining the structure of TDM-PON. It is a figure explaining the structure of WDM / TDM-PON. It is a figure explaining the structure of wavelength variable type WDM / TDM-PON. It is a figure explaining the structure of wavelength variable type WDM / TDM-PON. It is a figure explaining the structure of a wavelength variable transmitter. It is a figure explaining the structure of wavelength variable type WDM / TDM-PON. It is a figure explaining the discovery method which concerns on this invention. It is a figure explaining the structure of wavelength variable type WDM / TDM-PON. It is a figure explaining the discovery method which concerns on this invention. It is a figure explaining the structure of wavelength variable type WDM / TDM-PON. It is a figure explaining the discovery method which concerns on this invention. It is a figure explaining the structure of wavelength variable type WDM / TDM-PON.
- the optical communication system 301 transmits a downstream signal having wavelengths ⁇ D1 to ⁇ DM (M is an integer of 2 or more) and has wavelengths ⁇ U1 to ⁇ UN (N is an integer of 2 or more).
- a plurality of child nodes 200a that receive a downstream signal of a downstream wavelength and transmit an upstream signal at an allocated upstream wavelength;
- An optical fiber transmission line 250 connecting the parent node 100a and the plurality of child nodes 200a;
- An optical communication system comprising: The parent node 100a A table (not shown) for storing RTTs in all combinations of downstream wavelengths and upstream wavelengths for each identifier; The RTT corresponding to the combination of the downlink wavelength and the uplink wavelength assigned to the child node 200a is detected with reference to the table, and the allowable transmission time of the uplink signal is determined in consideration of the RTT and notified to the child node.
- a controller (not shown), Have
- the parent node 100a A plurality of optical transceivers 51 each having a unique downstream wavelength and a unique upstream wavelength set; Each of the optical transceivers 51 is connected to each of the optical transceivers 51.
- the downstream signals having different wavelengths from the optical transceivers 51 are wavelength-multiplexed and output to the optical fiber transmission line 250.
- the configuration of the optical communication system 301 is the same as that of the wavelength tunable WDM / TDM-PON in FIG.
- a parent node 100a that transmits downstream signal light having wavelengths ⁇ D1 to ⁇ DM (M is an integer of 2 or more) and receives upstream signal light having wavelengths ⁇ U1 to ⁇ UM is connected to ⁇ D1 to ⁇ DM , ⁇
- a plurality of child nodes (ONUs) 200a assigned from the parent node 100a with the respective wavelengths from U1 to ⁇ UM as the downstream wavelength and the upstream wavelength are connected via the optical fiber transmission line 250.
- each child node 200a When each child node 200a is newly registered in the parent node 100a, such as when it is first connected to the network, the child node 200a overlaps with the registered child node 200a as a unique identifier for each child node 200a through the discovery process.
- An identifier such as LLID is assigned so as not to occur.
- the identifier once assigned is fixedly assigned regardless of the change of the wavelength assigned to the child node 200a.
- the parent node 100a records the RTT of the frame between each child node 200a for all combinations of assigned wavelengths (see FIG. 17). (Not shown in FIG. 3) is created through the discovery process.
- LLID is used as an identifier.
- the parent node 100a has a plurality of OSUs 51.
- the OSU 51 includes an optical transmitter 11, wavelength multiplexing / demultiplexing means 12, and an optical receiver 15.
- the optical receiver 15 includes a wavelength filter 13 and a light receiver 14.
- the parent node 100a includes optical transmitters 11 # 1 to #M that transmit downlink signal lights of different wavelengths for downlink communication. Downstream signal light from each optical transmitter 11 is wavelength-multiplexed by the optical multiplexing / demultiplexing means 151 and then output to the optical fiber transmission line 250.
- Examples of the optical multiplexing / demultiplexing means 151 include an optical fiber and an optical coupler created by PLC (Planar Lightwave Circuit).
- FIG. 3 shows a configuration in which the optical multiplexing / demultiplexing means 151 has a plurality of terminals on the optical fiber transmission line 250 side, but a configuration having only a single terminal as shown in FIG. 4 is also possible.
- the child node 200a selectively receives the downlink signal light, which is the downlink wavelength assigned from the parent node 100a, from the input wavelength multiplexed signal light.
- the child node 200 a has an optical receiver 23.
- the optical receiver 23 includes a wavelength tunable filter 22 disposed in front of a light receiver 21 such as a PIN-PD (Photo-Diode) or APD (Avalanche Photo-Diode).
- a light receiver 21 such as a PIN-PD (Photo-Diode) or APD (Avalanche Photo-Diode).
- the child node 200a includes a tunable optical transmitter 24 capable of transmitting upstream signal light with wavelengths ⁇ U1 to ⁇ UM for upstream communication, and has an upstream wavelength assigned by the parent node 100a.
- Uplink signal light is transmitted within the allowable transmission time notified from 100a.
- the allowable transmission time notified from the parent node 100a is determined in consideration of the RTT described in the management table so that the signal lights from different child nodes 200a to which the same uplink wavelength is assigned do not collide with each other.
- a configuration in which the output light wavelength of a direct modulation laser such as a distributed feedback (DFB) laser is changed by temperature control, or a direct modulation laser having a different output light wavelength is arranged in an array.
- This corresponds to a configuration capable of high-speed wavelength switching for switching between lasers that emit light in response to an external control signal.
- the output light from the wavelength tunable light source is converted into a Mach-Zehnder modulator, an electroabsorption (EA) modulator, or a semiconductor optical amplifier (SOA) using a semiconductor or lithium diobate (LiNbO 3 ) as a material.
- EA electroabsorption
- SOA semiconductor optical amplifier
- a configuration for external modulation using a modulator or the like is also possible.
- variable wavelength light source a configuration in which continuous light (CW: Continuous Wave) lasers having different output light wavelengths are arranged in an array and the output light wavelength is switched by an external control signal corresponds to this.
- CW Continuous Wave
- DBR laser an external resonator type laser, or the like can be used as the wavelength tunable light source.
- the upstream signal light transmitted to the parent node 100a is branched by the optical multiplexing / demultiplexing means 151, and then input to the optical receivers 15 # 1 to #M that selectively receive upstream signal lights of different wavelengths.
- the wavelength filters 13 having different transmission wavelengths in the front stage of the light receiver 14 such as PIN-PD or APD, the upstream signal light having different wavelengths is received by each optical receiver 15. It can be received selectively.
- each child node 200a transmits the upstream signal light in which the identifier given to itself is embedded in the transmission frame, so that the parent node 100a can transmit the frame transmitted from which child node 200a by the identifier in the reception frame. It can be determined whether there is.
- 3 and 4 show a configuration in which only the wavelength of the desired signal light is transmitted by disposing the wavelength filter 13 or the wavelength tunable filter 22 before the light receiver (14, 21) at the child node 200a and the parent node 100a.
- coherent receivers (16, 27) may be used as the optical receivers in the child node 200b and the parent node 100b.
- the output light wavelength of the local light source 28 in the child node 200b is set near the wavelength of the assigned downstream signal light.
- the output light wavelength of the local light source 17 in the parent node 100b is set in the vicinity of one of the wavelengths ⁇ U1 to ⁇ UM so as to be different in each coherent receiver 16.
- the allowable loss in the optical fiber transmission line 250 or in the parent node 100b can be increased.
- the transmission distance can be extended and the number of child nodes 200b accommodated can be increased.
- the number of optical transceivers can be increased by increasing the branching loss allowed in the parent node 100b, the total system bandwidth can be expanded.
- the wavelength filter (13, 22) is not required by the application of coherent reception, it is possible to narrow the adjacent wavelength interval without being limited by the characteristics of the wavelength filter.
- FIG. 7 shows a procedure for assigning an identifier through the discovery process.
- the discovery method is a discovery method in a wavelength tunable WDM / TDM-PON in which a parent node 100a and a plurality of child nodes 200a are connected by an optical fiber transmission line 250.
- An identifier that is invariant when changing the wavelength is given to an unregistered child node 200a that has responded to the search signal transmitted by the parent node 100a with a response signal, Using the RTT between the parent node 100a and the child node 200a and the wavelength dependency of the refractive index of the optical fiber transmission line 250, the downstream wavelength and child node of the downlink signal from the parent node 100a to the child node 200a for each identifier.
- Ranging is performed for calculating RTTs in all combinations with upstream wavelengths of upstream signals from 200a to the parent node 100a, and RTTs in all the combinations calculated in the ranging are stored.
- a search signal if the received child node (200a, 200b) is not registered to the parent node (100a, 100b) and is not given an identifier, a response signal as a registration request is transmitted at a predetermined time. Instructions are listed.
- the transmission wavelength of the wavelength tunable filter 22 in the child nodes (200a, 200b) or the output light wavelength of the local light source 28 is ⁇ Dm .
- the wavelength control circuit in the child nodes (200a, 200b) may be set in advance so that the output optical wavelength of the wavelength tunable optical transmitter 24 is set to ⁇ Un .
- the response signal transmitted to the parent node (100a, 100b) is branched by the optical multiplexing / demultiplexing means 151 and then received by the optical receiver #n.
- LLID is used as an identifier.
- RTT is performed for all combinations of the downstream wavelength and the upstream wavelength allocated after registration to the child node (200a, 200b) #k. calculate. A method for calculating the RTT will be described below.
- the distance between the child node (200a, 200b) #k and the parent node (100a, 100b) is L k [km]
- the speed of light in vacuum is c [km / s]
- the wavelengths ⁇ Dm , ⁇ in the optical fiber transmission line 250 When the refractive index of Un is n Dm and n Un , It can be expressed as Therefore, the round-trip propagation time T k (when the wavelengths having the refractive indexes n Dm ′ and n Un ′ in the optical fiber transmission line 250 are assigned to the child nodes (200a, 200b) #k as the downstream wavelengths and the upstream wavelengths.
- ⁇ Dm ′ , ⁇ Un ′ Can be obtained as follows.
- the management table of FIG. 17 can be created by calculating this for all combinations of downstream wavelengths and upstream wavelengths that are assigned after registration to the child nodes (200a, 200b).
- the optical communication method of the optical communication system 301 is an optical communication method in a wavelength tunable WDM / TDM-PON in which a parent node 100a and a plurality of child nodes 200a are connected by an optical fiber transmission line 250.
- the identifier assigned to the child node 200a is unchanged when the wavelength is changed, Storing RTTs in all combinations of the downstream wavelength of the downstream signal from the parent node 100a to the child node 200a and the upstream wavelength of the upstream signal from the child node 200a to the parent node 100a for each identifier;
- the RTT corresponding to the combination of the downstream wavelength and the upstream wavelength assigned to the child node 200a is detected with reference to the table, and the allowable transmission time of the upstream signal is determined in consideration of the RTT and notified to the child node 200a. To do. Then, RTTs for all the combinations are calculated by the ranging performed by the discovery method.
- the identifier given through the discovery process at the time of new registration of the child nodes (200a, 200b) is fixedly given even after the assigned wavelength is changed, and information for all the child nodes (200a, 200b) combined with the RTT. 17 is provided in the parent node (100a, 100b) as shown in FIG. 17, it is not necessary to redo the discovery process when the allocated wavelength is changed. Furthermore, since RTT is described for all combinations of downstream wavelengths and upstream wavelengths assigned to the child nodes (200a, 200b) in FIG. 17, the parent node (100a, 100b) is assigned to each child node (200a, 200b). When determining the transmission timing of the upstream signal light, highly accurate RTT information can be used regardless of the assigned wavelength. Therefore, it is possible to reduce the guard interval between the upstream signal lights from different child nodes (200a, 200b) and improve the band utilization efficiency.
- FIG. 8 shows a configuration of a wavelength tunable WDM / TDM-PON which is the optical communication system 302 in the second embodiment.
- the optical communication system 302 includes a parent node 100c, a child node 200c, and an optical fiber transmission line 250.
- the parent node 100c of the optical communication system 302 A plurality of optical transceivers 51 capable of setting downstream wavelengths of wavelengths ⁇ D1 to ⁇ DM ;
- Each optical transmitter / receiver 51 is connected via an optical transmitter / receiver side terminal, and the downstream signal from the optical transmitter / receiver 51 is output from a different optical fiber transmission line side terminal according to the downstream wavelength and coupled to the optical fiber transmission line 250.
- a wavelength routing unit 152 that outputs an upstream signal from the optical fiber transmission line 250 input to the optical fiber transmission line side terminal from the optical transceiver side terminal that differs according to an upstream wavelength and couples to the optical transceiver 51; , Have The controller is At the time of discovery, a plurality of optical transceivers 51 are caused to transmit a search signal of one downstream wavelength, and the discovery method is performed using a response signal transmitted by an unregistered child node 200c received by any one of the optical transceivers 51. Execute.
- the parent node 100c is configured to use wavelength routing means 152 that distributes input light according to the wavelength and outputs it from different terminals, instead of the optical multiplexing / demultiplexing means 151 in the parent node in the first embodiment.
- each child node 200c is fixedly assigned an identifier such as LLID given through the discovery process regardless of the change of the assigned wavelength, and the parent node 100c is assigned to each child node.
- a management table as shown in FIG. 17 is provided in which RTTs of frames between the child nodes 200c are recorded for all combinations of assigned wavelengths.
- LLID is used as an identifier.
- the parent node 100c includes variable wavelength optical transmitters 18 # 1 to #M that can transmit downlink signal light having wavelengths ⁇ D1 to ⁇ DM .
- Downstream signal light from each of the wavelength tunable optical transmitters 18 is input to the wavelength routing unit 152 through separate optical transmitter / receiver side terminals, and is output to the optical fiber transmission line 250 from different optical fiber transmission line side terminals depending on the wavelength. Is done.
- the wavelength tunable optical transmitter 18 changes the transmission wavelength of the downstream signal light in accordance with which optical fiber transmission line side terminal is connected to the child node 200c that is the destination of the frame through the optical fiber transmission line 250.
- the number H of optical fiber transmission line side terminals (H is an integer of 1 or more) is equal to or less than the number M of optical transceiver side terminals, and the wavelengths ⁇ D1 to ⁇ input from the respective optical transceiver side terminals.
- an AWG Arrayed Waveguide Grating
- the like that distributes the DM light to optical fiber transmission line side terminals # 1 to #H according to the wavelength is used.
- the child node 200c is connected to one of the optical fiber transmission line side terminals of the wavelength routing means 152 in the parent node 100c via the optical fiber transmission line 250, and receives the downstream signal light output from the terminal to be connected.
- Each child node 200c uses the identifier to determine whether the received frame is addressed to itself, and selects a received frame.
- the child node 200c includes a tunable optical transmitter 24 that can transmit uplink signal light having wavelengths ⁇ U1 to ⁇ UM , and has an upstream wavelength assigned by the parent node 100c.
- Uplink signal light is transmitted within the allowable transmission time notified from 100c.
- the allowable transmission time notified from the parent node 100c is the RTT described in the management table (not shown in FIG. 8) so that upstream signal lights destined for the same optical receiver 19 in the parent node 100c do not collide with each other. Decided in consideration.
- the configuration of the wavelength tunable optical transmitter 24 is the same as that described in the first embodiment.
- the upstream signal light transmitted to the parent node 100c is distributed according to the wavelength by the wavelength routing means 152, and is input to the optical receiver 19 through a different optical transceiver side terminal.
- each child node 200c transmits the upstream signal light in which the identifier given to itself is embedded in the transmission frame, so that the parent node 100c can transmit the frame transmitted from which child node 200c by the identifier in the reception frame. It can be determined whether there is.
- the wavelength routing means 152 the light of the wavelengths ⁇ U1 to ⁇ UM inputted from the respective optical fiber transmission line side terminals # 1 to #H is changed according to the wavelength as shown in FIG. An AWG that distributes to #M is used.
- the coherent receiver described in FIG. 6 may be used as the optical receivers (19, 29) in the child node 200c and the parent node 100c.
- the output light wavelength of the local light source in the child node 200c is set near the wavelength of the assigned downstream signal light.
- the output light wavelength of the local light source in the parent node 100c is changed according to which child node 200c the upstream signal light arriving at the optical receiver is transmitted.
- coherent reception characterized by high reception sensitivity the allowable loss in the optical fiber transmission line 250 can be increased.
- the transmission distance can be extended and the number of child nodes 200c accommodated can be increased.
- FIG. 9 shows a procedure for assigning an identifier through the discovery process.
- All or a plurality of the tunable optical transmitters 18 in the parent node 100c transmit a search signal at a wavelength ⁇ Dm at a predetermined time.
- all the wavelength variable transmitters 18 transmit search signals so that the optical fiber is transmitted through all the optical fiber transmission line terminals.
- a search signal can be output to the transmission line 250.
- the H wavelength variable transmitters 18 transmit the search signals, so that the optical fiber transmission lines 250 pass through all the optical fiber transmission line terminals.
- a search signal can be output.
- the search signal describes an instruction to transmit a response signal as a registration request when the received child node 200c is not registered with the parent node 100c and is not given an identifier.
- the child node 200c is set so that the output light wavelength of the local light source in the unregistered child node 200c is in the vicinity of ⁇ Dm. By setting the internal wavelength control circuit in advance, the unregistered child node 200c can reliably receive the search signal.
- the unregistered child node can also search for the search signal by a method of periodically sweeping the output light wavelength of the local light source in the child node in the range of l D — 1 to l D — M. It can be received reliably.
- the wavelength designation of the response signal may include a command to set the wavelength of the response signal to ⁇ Un in the search signal.
- the output optical wavelength of the tunable optical transmitter is set.
- wavelength control circuit Yoko node 200c is set to lambda Un may be set in advance.
- the response signal transmitted to the parent node 100 c is distributed according to the wavelength by the wavelength routing unit 152 and then received by the optical receiver 19.
- FIG. 9 shows a configuration in which a response signal is output to the optical receiver from the same terminal as the optical transmitter / receiver side terminal in which the search signal is input to the wavelength routing unit 152, the search signal may be output from a different terminal.
- LLID is used as an identifier.
- the parent node 100c When the parent node 100c receives a response signal that is a registration request from the unregistered child node 200c # k, as in the first embodiment, the parent node 100c does not overlap with the registered child node 200c. An identifier is assigned to the child node 200c # k of the transmission source. At the same time, from the time T k ( ⁇ Dm , ⁇ Un ) required for transmission / reception of the search signal and the response signal, the RTT is calculated for all combinations of the downstream wavelength and the upstream wavelength assigned after registration to the child node 200c # k. 17 management tables are created.
- the identifier given through the discovery process at the time of new registration of the child node 200c is fixedly given after the change of the assigned wavelength, and information for all the child nodes 200c combined with the RTT is described as shown in FIG. Since the management table is provided in the parent node 100c, it is not necessary to redo the discovery process associated with the change of the assigned wavelength. Further, since RTT is described for all combinations of downstream wavelengths and upstream wavelengths to be assigned to the child node 200c in FIG. 17, when the parent node 100c determines the transmission timing of the upstream signal light of each child node 200c, RTT information with high accuracy can be used regardless of the assigned wavelength. Therefore, it is possible to reduce the guard interval between the upstream signal lights from different child nodes 200c and improve the band utilization efficiency.
- FIG. 10 shows the configuration of a wavelength tunable WDM / TDM-PON which is an optical communication system 302a in the third embodiment.
- the optical communication system 302a is obtained by replacing the child node 200c of the second embodiment with the child node 200a of the first embodiment. That is, the child node 200a arranges the wavelength tunable filter 22 in front of the light receiver 21, and changes the transmission wavelength of the wavelength tunable filter 22 in accordance with the assigned downstream wavelength, thereby allowing the downstream signal light having a desired wavelength to be transmitted. It is the structure which receives selectively.
- downstream signal light having different wavelengths can be wavelength-multiplexed and transmitted in the optical fiber transmission line 250. Therefore, different child nodes in the child node group connected via the optical fiber transmission line 250 with the same optical fiber transmission line side terminal of the wavelength routing unit 152 can simultaneously receive the downlink signal light.
- the coherent receiver described in FIG. 6 may be used as the optical receivers (23, 19) in the child node 200a and the parent node 100c.
- the output light wavelength of the local light source in the child node is set near the wavelength of the assigned downstream signal light.
- the output light wavelength of the local light source in the parent node is changed according to which child node the upstream signal light arriving at the optical receiver is transmitted.
- each child node 200a is fixedly assigned an identifier such as LLID given through the discovery process regardless of the change of the assigned wavelength, and the parent node 100c is assigned to each child node.
- a management table as shown in FIG. 17 is provided in which RTTs of frames between the child nodes 200a are recorded for all combinations of assigned wavelengths.
- LLID is used as an identifier.
- the management table as shown in FIG. 17 is created in the same manner as in the second embodiment through the discovery process.
- the transmission wavelength of the wavelength tunable filter 22 in the child node 200a or the output light wavelength of the local light source becomes ⁇ Dm .
- the unregistered child node 200a can reliably receive the search signal.
- the transmission wavelength of the tunable filter 22 in the child node or the output light wavelength of the local light source is periodically not swept within a range of l D_1 to l D_M. The registered child node can reliably receive the search signal.
- the identifier given through the discovery process at the time of new registration of the child node 200a is fixedly given even after the change of the assigned wavelength, and the information for all the child nodes 200a together with the RTT is described as shown in FIG. Since the management table is provided in the parent node 100c, it is not necessary to redo the discovery process associated with the change of the assigned wavelength. Further, since RTT is described for all combinations of downstream wavelengths and upstream wavelengths assigned to the child node 200a in FIG. 17, when the parent node 100c determines the transmission timing of the upstream signal light of each child node 200a, RTT information with high accuracy can be used regardless of the assigned wavelength. Therefore, it is possible to reduce the guard interval between the upstream signal lights from different child nodes 200a and improve the band utilization efficiency.
- the optical communication system of the present embodiment is the same as the configuration of the optical communication system (FIGS. 3 to 4 and FIG. 6) described in the first embodiment, but the parent nodes are all ⁇ D1 to ⁇ DM during discovery.
- a search signal is transmitted at a wavelength. That is, the parent node 100a
- a plurality of optical transceivers 51 capable of setting at least one of the downstream wavelengths of wavelengths ⁇ D1 to ⁇ DM ;
- Each of the optical transceivers 51 is connected to each of the optical transceivers 51.
- the downstream signals having different wavelengths from the optical transceivers 51 are wavelength-multiplexed and output to the optical fiber transmission line 250.
- Optical multiplexing / demultiplexing means 151 coupled to the transceiver 51; Have The controller is At the time of discovery, the search signal of a plurality of downstream wavelengths is transmitted using at least one optical transceiver 51, and the response signal transmitted by the unregistered child node 200a received by any one of the optical transceivers 51 is used. Run the discovery method.
- each child node (200a, 200b) is fixedly assigned an identifier such as LLID given through the discovery process regardless of the change of the assigned wavelength, and the parent node (100a, 200b, 100b) records the RTT of the frame between each child node (200a, 200b) and all the combinations of the assigned wavelengths in addition to the correspondence between each child node (200a, 200b) and the identifier.
- the management table is provided. In FIG. 17, LLID is used as an identifier.
- FIG. 11 shows a procedure for assigning an identifier through the discovery process.
- All the optical transmitters 11 in the parent nodes (100a, 100b) transmit search signals at different wavelengths at a predetermined time.
- the search signal includes an instruction to transmit a response signal as a registration request when the received child node (200a, 200b) is not registered with the parent node (100a, 100b) and is not assigned an identifier. ing.
- the transmission wavelength of the tunable filter 22 in the child nodes (200a, 200b) or the output light wavelength of the local light source 28 is any of ⁇ D1 to ⁇ DM .
- the unregistered child nodes (200a, 200b) can reliably receive the search signal.
- the transmission wavelength of the tunable filter 22 in the child node or the output light wavelength of the local light source is periodically not swept within a range of l D_1 to l D_M.
- the registered child node can reliably receive the search signal.
- a command to set the wavelength of the response signal to any one of ⁇ U1 to ⁇ UM may be included in the search signal.
- the response signal transmitted to the parent node (100a, 100b) is branched by the optical multiplexing / demultiplexing means 151 and then received by the optical receiver 15 # n or the coherent receiver 16 # n.
- LLID is used as an identifier.
- search signals of wavelengths ⁇ D1 to ⁇ DM are transmitted using all the optical transmitters 11 in the parent nodes (100a, 100b). However, as shown in FIG. 12, any one optical transmitter 11 is used. However, the search signals of wavelengths ⁇ D1 to ⁇ DM may be time-multiplexed and transmitted. In this case, at least the optical transmitter 11 that transmits the search signal is a variable wavelength optical transmitter that can transmit the downstream signal light having the wavelengths ⁇ D1 to ⁇ DM .
- the parent node (100a, 100b) receives a response signal that is a registration request from an unregistered child node (200a, 200b) #k, as in the first embodiment, the registered child node ( 200a and 200b), an identifier is assigned to the child node #k of the transmission source so as not to overlap.
- RTT is performed for all combinations of the downstream wavelength and the upstream wavelength allocated after registration to the child node (200a, 200b) #k.
- the management table shown in FIG. 17 is created by calculation.
- the identifier given through the discovery process at the time of new registration of the child nodes (200a, 200b) is fixedly given even after the assigned wavelength is changed, and information for all the child nodes (200a, 200b) combined with the RTT. 17 is provided in the parent node (100a, 100b) as shown in FIG. 17, it is not necessary to redo the discovery process when the allocated wavelength is changed. Furthermore, since RTT is described for all combinations of downstream wavelengths and upstream wavelengths assigned to the child nodes (200a, 200b) in FIG. 17, the parent node (100a, 100b) is assigned to each child node (200a, 200b). When determining the transmission timing of the upstream signal light, highly accurate RTT information can be used regardless of the assigned wavelength. Therefore, it is possible to reduce the guard interval between the upstream signal lights from different child nodes (200a, 200b) and improve the band utilization efficiency.
- the optical communication system of the present embodiment has the same configuration as that of the optical communication system (FIG. 8) described in the second embodiment or the optical communication system (FIG. 10) described in the third embodiment. Transmits a search signal at all or a plurality of wavelengths of ⁇ D1 to ⁇ DM . That is, the parent node 100c A plurality of optical transceivers 51 capable of setting downstream wavelengths of wavelengths ⁇ D1 to ⁇ DM ; Each optical transmitter / receiver 51 is connected via an optical transmitter / receiver side terminal, and the downstream signal from the optical transmitter / receiver 51 is output from a different optical fiber transmission line side terminal according to the downstream wavelength and coupled to the optical fiber transmission line 250.
- a wavelength routing unit 152 that outputs an upstream signal from the optical fiber transmission line 250 input to the optical fiber transmission line side terminal from the optical transceiver side terminal that differs according to an upstream wavelength and couples to the optical transceiver 51; , Have The controller is At the time of discovery, one optical transceiver 51 transmits a plurality of downstream wavelength search signals, and the discovery method is performed using a response signal transmitted by an unregistered child node 200c received by any one of the optical transceivers 51. Execute.
- each child node 200c is fixedly assigned an identifier such as an LLID given through the discovery process regardless of the change of the assigned wavelength, and the parent node 100c is assigned to each child node.
- an identifier such as an LLID given through the discovery process regardless of the change of the assigned wavelength
- the parent node 100c is assigned to each child node.
- a management table as shown in FIG. 17 is provided in which RTTs of frames between the child nodes 200c are recorded for all combinations of assigned wavelengths.
- LLID is used as an identifier.
- FIG. 13 shows a procedure for assigning an identifier through the discovery process.
- any one optical transmitter 18 in the parent node 100c time-multiplexes and transmits the search signal at all or a plurality of wavelengths of ⁇ D1 to ⁇ DM .
- the search signal is transmitted at all wavelengths of ⁇ D1 to ⁇ DM , so that all optical fiber transmission line sides
- a search signal can be output to the optical fiber transmission line 250 through the terminal.
- the search signal is transmitted at H wavelengths from ⁇ D1 to ⁇ DM , so that the light is transmitted through all the optical fiber transmission line side terminals.
- a search signal can be output to the fiber transmission line 250.
- the search signal describes an instruction to transmit a response signal as a registration request when the received child node 200c is not registered with the parent node 100c and is not given an identifier.
- the unregistered child node 200c performs a method of periodically sweeping the transmission wavelength of the wavelength tunable filter 22 or the output light wavelength of the local light source in the range of l D_1 to l D_M . Unregistered child nodes can reliably receive the search signal.
- the wavelength designation of the response signal may include an instruction to set the wavelength of the response signal to ⁇ Un in the search signal, or when the search signal of ⁇ Dm is received, the output optical wavelength of the wavelength tunable optical transmitter 24
- the wavelength control circuit in the child node 200c may be set in advance so as to set ⁇ Un to ⁇ Un .
- the response signal transmitted to the parent node 100 c is distributed according to the wavelength by the wavelength routing unit 152 and then received by the optical receiver 19.
- FIG. 13 shows a configuration in which the response signal is output to the optical receiver 19 from the same terminal as the optical transmitter / receiver side terminal in which the search signal is input to the wavelength routing unit 152, but may be output from a different terminal.
- LLID is used as an identifier.
- the parent node 100c When the parent node 100c receives a response signal that is a registration request from the unregistered child node 200c # k, as in the second embodiment, the parent node 100c does not overlap with the registered child node 200c. An identifier is assigned to the child node 200c # k of the transmission source. At the same time, from the time T k ( ⁇ Dm , ⁇ Un ) required for transmission / reception of the search signal and the response signal, the RTT is calculated for all combinations of the downstream wavelength and the upstream wavelength assigned after registration to the child node 200c # k. 17 management tables are created.
- the identifier given through the discovery process at the time of new registration of the child node 200c is fixedly given after the change of the assigned wavelength, and information for all the child nodes 200c combined with the RTT is described as shown in FIG. Since the management table is provided in the parent node 100c, it is not necessary to redo the discovery process associated with the change of the assigned wavelength. Further, since RTT is described for all combinations of downstream wavelengths and upstream wavelengths to be assigned to the child node 200c in FIG. 17, when the parent node 100c determines the transmission timing of the upstream signal light of each child node 200c, RTT information with high accuracy can be used regardless of the assigned wavelength. Therefore, it is possible to reduce the guard interval between the upstream signal lights from different child nodes 200c and improve the band utilization efficiency.
- FIG. 14 shows the configuration of a wavelength tunable WDM / TDM-PON that is an optical communication system according to the sixth embodiment.
- the difference from the wavelength tunable WDM / TDM-PON configuration in the fifth embodiment is that the number M of optical fiber transmission line side terminals of the wavelength routing means 152 in the parent node is larger than the number H of optical transceiver side terminals. That is.
- the input / output relationship of downstream signal light and upstream signal light in the wavelength routing means 152 is shown in FIGS. 20 and 21, respectively.
- each child node 200c is fixedly assigned an identifier such as LLID given through the discovery process regardless of the change of the assigned wavelength, and the parent node 100c is assigned to each child node.
- an identifier such as LLID given through the discovery process regardless of the change of the assigned wavelength
- the parent node 100c is assigned to each child node.
- a management table as shown in FIG. 17 is provided in which RTTs of frames between the child nodes 200c are recorded for all combinations of assigned wavelengths.
- LLID is used as an identifier.
- FIG. 15 shows a procedure for assigning an identifier through the discovery process.
- Any one optical transmitter in the parent node 100c time-multiplexes and transmits a search signal of wavelengths ⁇ D1 to ⁇ DM . Thereby, a search signal can be output to the optical fiber transmission line 250 through all the optical fiber transmission line side terminals.
- the search signal describes an instruction to transmit a response signal as a registration request when the received child node 200c is not registered with the parent node 100c and is not given an identifier.
- the unregistered child node 200c periodically sweeps the transmission wavelength of the wavelength tunable filter 22 or the output light wavelength of the local light source in the range of l D — 1 to l D — M. Unregistered child nodes can reliably receive the search signal.
- the wavelength designation of the response signal may include a command for setting the wavelength of the response signal to ⁇ Un in the search signal.
- the output optical wavelength of the tunable optical transmitter 24 The wavelength control circuit in the child node 200c may be set in advance so as to set ⁇ Un to ⁇ Un .
- the response signal transmitted to the parent node 100 c is distributed according to the wavelength by the wavelength routing unit 152 and then received by the optical receiver 19.
- FIG. 15 shows a configuration in which the response signal is output to the optical receiver from the same terminal as the optical transmitter / receiver side terminal in which the search signal is input to the wavelength routing unit 152, but may be output from a different terminal.
- LLID is used as an identifier.
- the parent node 100c When the parent node 100c receives a response signal that is a registration request from the unregistered child node 200c # k, as in the second embodiment, the parent node 100c does not overlap with the registered child node 200c. An identifier is assigned to the child node 200c # k of the transmission source. At the same time, from the time T k ( ⁇ Dm , ⁇ Un ) required for transmission / reception of the search signal and the response signal, the RTT is calculated for all combinations of the downstream wavelength and the upstream wavelength assigned after registration to the child node 200c # k. 17 management tables are created.
- the identifier given through the discovery process at the time of new registration of the child node 200c is fixedly given after the change of the assigned wavelength, and information for all the child nodes 200c combined with the RTT is described as shown in FIG. Since the management table is provided in the parent node 100c, it is not necessary to redo the discovery process associated with the change of the assigned wavelength. Further, since RTT is described for all combinations of downstream wavelengths and upstream wavelengths to be assigned to the child node 200c in FIG. 17, when the parent node 100c determines the transmission timing of the upstream signal light of each child node 200c, RTT information with high accuracy can be used regardless of the assigned wavelength. Therefore, it is possible to reduce the guard interval between the upstream signal lights from different child nodes 200c and improve the band utilization efficiency.
- the following describes the discovery method, optical communication method, and optical communication system of the present embodiment.
- one parent node and a plurality of child nodes are connected via an optical fiber transmission line 250;
- the parent node transmits downstream signal light having wavelengths ⁇ D1 to ⁇ DM (M is an integer of 2 or more), and upstream signal light having wavelengths ⁇ U1 to ⁇ UN (N is an integer of 2 or more) is input.
- the child nodes registered in the parent node are assigned with wavelengths of ⁇ D1 to ⁇ DM and ⁇ U1 to ⁇ UN by the parent node as a downstream wavelength and an upstream wavelength, respectively.
- a discovery method for registering the child node The parent node transmits a search signal to all the child nodes, The child node that is unregistered with the parent node among the child nodes transmits a response signal toward the parent node when receiving the search signal, The parent node, when receiving the response signal, registers the child node of the transmission source corresponding to a unique identifier for each child node, and from the time required for transmission and reception of the search signal and the response signal, A discovery method characterized by storing a round-trip propagation time of a frame with the child node for all combinations of the downstream wavelength and the upstream wavelength assigned after registration to the child node.
- the parent node transmits the search signal at a single wavelength;
- the parent node includes a plurality of optical transceivers and optical multiplexing / demultiplexing means 151,
- the plurality of optical transceivers transmit and receive signal light having a unique wavelength for each optical transceiver
- the optical multiplexing / demultiplexing means 151 is connected to each of the optical transceivers, and a master node that wavelength-multiplexes the downstream signal lights having different wavelengths from the plurality of optical transceivers and outputs them to the optical fiber transmission line 250.
- One of the optical transceivers transmits the search signal at the single wavelength;
- the discovery method according to (3) wherein the response signal transmitted by the child node is branched by the optical multiplexing / demultiplexing means 151 and then received by any one of the optical transceivers. .
- the parent node includes a plurality of optical transceivers and wavelength routing means 152,
- the plurality of optical transceivers can transmit / receive signal light having wavelengths ⁇ D1 to ⁇ DM / ⁇ U1 to ⁇ UN ,
- the wavelength routing means 152 is connected to each optical transceiver via a separate optical transceiver side terminal, and the downstream signal light from the plurality of optical transceivers is different depending on the wavelength.
- the optical communication system which is a parent node that outputs to the optical fiber transmission line 250 from All or a plurality of the optical transceivers transmit the search signal having the single wavelength;
- the response signal transmitted by the child node is received by any one of the optical transceivers via the different optical transceiver side terminals by the wavelength routing means 152.
- the parent node transmits the search signal at all or a plurality of wavelengths of ⁇ D1 to ⁇ DM ,
- the child node that is unregistered with the parent node can receive the search signal that is at least one of a plurality of wavelengths of ⁇ D1 to ⁇ DM or a plurality of wavelengths.
- the discovery method according to (1) or (2).
- the parent node includes a plurality of optical transceivers and optical multiplexing / demultiplexing means 151,
- the plurality of optical transceivers transmit and receive signal light having a unique wavelength for each optical transceiver
- the optical multiplexing / demultiplexing means 151 is connected to each of the optical transceivers, and a master node that wavelength-multiplexes the downstream signal lights having different wavelengths from the plurality of optical transceivers and outputs them to the optical fiber transmission line 250.
- the optical transceiver that transmits the search signal if there is the optical transceiver that transmits the search signal of a plurality of wavelengths, at least the optical transceiver can change the transmission optical wavelength, Transmit the search signals of a plurality of wavelengths in a time-multiplexed manner,
- the parent node includes a plurality of optical transceivers and wavelength routing means 152,
- the plurality of optical transceivers can transmit / receive signal light having wavelengths ⁇ D1 to ⁇ DM / ⁇ U1 to ⁇ UN ,
- the wavelength routing means 152 is connected to each optical transceiver via a separate optical transceiver side terminal, and the downstream signal light from the plurality of optical transceivers is different depending on the wavelength.
- the optical communication system which is a parent node that outputs to the optical fiber transmission line 250 from The optical transceiver transmits the search signal in a time-multiplexed manner with all or a plurality of wavelengths of ⁇ D1 to ⁇ DM ;
- the response signal transmitted by the child node is received by any one of the optical transceivers via the optical transceiver side terminal that differs depending on the wavelength by the wavelength routing unit 152.
- One parent node and a plurality of child nodes are connected via an optical fiber transmission line 250;
- the parent node transmits downstream signal light having wavelengths ⁇ D1 to ⁇ DM (M is an integer of 2 or more), and upstream signal light having wavelengths ⁇ U1 to ⁇ UN (N is an integer of 2 or more) is input.
- Each of the child nodes is assigned the wavelength from ⁇ D1 to ⁇ DM and ⁇ U1 to ⁇ UN as a downstream wavelength and an upstream wavelength from the parent node, and has the same wavelength as the allocated downstream wavelength.
- An optical communication method of an optical communication system that receives downlink signal light and transmits the signal light at the assigned upstream wavelength, In the parent node, all the combinations of the downstream wavelength and the upstream wavelength assigned to each of the child nodes are stored so that the signal lights transmitted from different child nodes to which the same upstream wavelength is assigned do not collide with each other.
- one parent node and a plurality of child nodes are connected via an optical fiber transmission line 250;
- the parent node transmits downstream signal light having wavelengths ⁇ D1 to ⁇ DM (M is an integer of 2 or more), and upstream signal light having wavelengths ⁇ U1 to ⁇ UN (N is an integer of 2 or more) is input.
- Each of the child nodes is assigned the wavelength from ⁇ D1 to ⁇ DM and ⁇ U1 to ⁇ UN as a downstream wavelength and an upstream wavelength from the parent node, and has the same wavelength as the allocated downstream wavelength.
- An optical communication system that receives downstream signal light and transmits the upstream signal light at the allocated upstream wavelength;
- Each child node is given a unique identifier for each child node,
- the parent node is configured to transmit a frame between each of the child nodes with respect to all combinations of the downstream wavelength and the upstream wavelength assigned to each of the child nodes.
- An optical communication system comprising a management table that records a round-trip propagation time.
- the child node transmits the uplink signal light having a frame length notified from the parent node at a transmission time notified from the parent node,
- the notification from the parent node takes into account the round-trip propagation time described in the management table so that the upstream signal lights from different child nodes to which the same upstream wavelength is assigned do not collide,
- the parent node includes a plurality of optical transceivers and optical multiplexing / demultiplexing means 151,
- the plurality of optical transceivers transmit and receive the downstream signal light having a unique wavelength for each optical transceiver
- the optical multiplexing / demultiplexing means 151 is connected to each of the optical transceivers, wavelength-multiplexes the downstream signal lights having different wavelengths from the plurality of optical transceivers, and outputs the multiplexed signals to the optical fiber transmission line 250.
- the upstream signal light transmitted by the child node is branched by the optical multiplexing / demultiplexing means 151 and then received by any of the optical transceivers (10) or (11)
- the parent node includes a plurality of optical transceivers and wavelength routing means 152,
- the plurality of optical transceivers can transmit / receive signal light having wavelengths ⁇ D1 to ⁇ DM / ⁇ U1 to ⁇ UN
- the wavelength routing means 152 is connected to each optical transceiver via a separate optical transceiver side terminal, and the downstream signal light from the plurality of optical transceivers is different depending on the wavelength.
- the optical communication system which is a parent node that outputs to the optical fiber transmission line 250 from The upstream signal light transmitted by the child node is received by any one of the optical transceivers through the optical transceiver side terminal that differs depending on the wavelength by the wavelength routing means 152.
- the optical communication system according to (10) or (11) above.
- Optical transmitter 12 Wavelength multiplexing / demultiplexing means 13: Wavelength filter 14: Light receiver 15: Optical receiver 16: Coherent receiver 17: Local light source 18: Wavelength variable optical transmitter 19: Optical receiver 21: Light reception Unit 22: wavelength tunable filter 23: optical receiver 24: wavelength tunable optical transmitter 26: wavelength multiplexing / demultiplexing means 27: coherent receiver 28: local light source 51: OSU 100a, 100b, 100c: parent node 151: optical multiplexing / demultiplexing means 152: wavelength routing means 200, 200a, 200b, 200c: child node 250: optical fiber transmission line 300, 300a, 301, 301a, 301b, 302, 302a, 302b : Optical communication system
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Abstract
Description
前記親ノードが送信した探索信号に応答信号で応答した未登録の前記子ノードに波長変更時に不変である識別子を付与するとともに、
前記親ノードと前記子ノードとの間の往復伝搬時間(RTT:Round Trip Time)及び前記光ファイバ伝送路の屈折率の波長依存性を用いて、前記識別子毎に前記親ノードから前記子ノードへの下り信号の下り波長と前記子ノードから前記親ノードへの上り信号の上り波長との全ての組み合わせにおけるRTTを算出するレンジングを行い、前記レンジングで算出した前記全ての組み合わせにおけるRTTを記憶することを特徴とする。
前記子ノードに付与した識別子を波長変更時に不変とし、
前記識別子毎に前記親ノードから前記子ノードへの下り信号の下り波長と前記子ノードから前記親ノードへの上り信号の上り波長との全ての組み合わせにおけるRTTをテーブルに記憶し、
前記テーブルを参照して前記子ノードに割り当てられている下り波長と上り波長の組み合わせに対応するRTTを検出し、前記RTTを考慮して上り信号の送信許容時間を決定して前記子ノードに通知することを特徴とする。
それぞれに波長変更時に不変である識別子が付与され、下り波長として波長λD1~λDMのいずれか一つ、上り波長として波長λU1~λUNのいずれか一つが前記親ノードから割り当てられ、割り当てられている下り波長の下り信号を受信し、割り当てられている上り波長で上り信号を送出する複数の子ノードと、
前記親ノードと複数の前記子ノードとを接続する光ファイバ伝送路と、
を備える光通信システムであって、
前記親ノードは、
前記識別子毎に下り波長と上り波長との全ての組み合わせにおけるRTTを記憶するテーブルと、
前記テーブルを参照して前記子ノードに割り当てられている下り波長と上り波長の組み合わせに対応するRTTを検出し、前記RTTを考慮して上り信号の送信許容時間を決定して前記子ノードに通知する制御器と、
を有することを特徴とする。
それぞれ固有の下り波長と固有の上り波長が設定される複数の光送受信器と、
各々の前記光送受信器と接続され、前記光送受信器からの波長の相異なる下り信号を波長多重して前記光ファイバ伝送路に出力し、前記光ファイバ伝送路からの上り信号を分岐して前記光送受信器に結合する光合分波手段と、
を有しており、
前記制御器は、
ディスカバリ時に、1の前記光送受信器に1の下り波長の探索信号を送信させるとともに、いずれかの前記光送受信器で受信した未登録の前記子ノードが送信する応答信号を用いて前記ディスカバリ方法を実行することを特徴とする。
波長λD1~λDMの下り波長が設定可能な複数の光送受信器と、
各々の前記光送受信器が光送受信器側端子を介して接続され、前記光送受信器からの前記下り信号を下り波長に応じて異なる光ファイバ伝送路側端子から出力して前記光ファイバ伝送路に結合し、前記光ファイバ伝送路側端子に入力された前記光ファイバ伝送路からの上り信号を上り波長に応じて異なる前記光送受信器側端子から出力して前記光送受信器に結合する波長ルーティング手段と、
を有しており、
前記制御器は、
ディスカバリ時に、複数の前記光送受信器に1の下り波長の探索信号を送信させるとともに、いずれかの前記光送受信器で受信した未登録の前記子ノードが送信する応答信号を用いて前記ディスカバリ方法を実行することを特徴とする。
波長λD1~λDMの下り波長のうちの少なくとも1波長が設定可能な複数の光送受信器と、
各々の前記光送受信器と接続され、前記光送受信器からの波長の相異なる下り信号を波長多重して前記光ファイバ伝送路に出力し、前記光ファイバ伝送路からの上り信号を分岐して前記光送受信器に結合する光合分波手段と、
を有しており、
前記制御器は、
ディスカバリ時に、少なくとも1の前記光送受信器を用いて複数の下り波長の探索信号を送信させるとともに、いずれかの前記光送受信器で受信した未登録の前記子ノードが送信する応答信号を用いて前記ディスカバリ方法を実行することを特徴とする。
波長λD1~λDMの下り波長が設定可能な複数の光送受信器と、
各々の前記光送受信器が光送受信器側端子を介して接続され、前記光送受信器からの前記下り信号を下り波長に応じて異なる光ファイバ伝送路側端子から出力して前記光ファイバ伝送路に結合し、前記光ファイバ伝送路側端子に入力された前記光ファイバ伝送路からの上り信号を上り波長に応じて異なる前記光送受信器側端子から出力して前記光送受信器に結合する波長ルーティング手段と、
を有しており、
前記制御器は、
ディスカバリ時に、1の前記光送受信器に複数の下り波長の探索信号を送信させるとともに、いずれかの前記光送受信器で受信した未登録の前記子ノードが送信する応答信号を用いて前記ディスカバリ方法を実行することを特徴とする。
第1の実施形態の光通信システム301は、波長λD1~λDM(Mは2以上の整数)である下り信号を送出し、波長λU1~λUN(Nは2以上の整数)である上り信号が入力される親ノード100aと、
それぞれに波長変更時に不変である識別子が付与され、下り波長として波長λD1~λDMのいずれか一つ、上り波長として波長λU1~λUNのいずれか一つが前記親ノードから割り当てられ、割り当てられている下り波長の下り信号を受信し、割り当てられている上り波長で上り信号を送出する複数の子ノード200aと、
親ノード100aと複数の子ノード200aとを接続する光ファイバ伝送路250と、
を備える光通信システムであって、
親ノード100aは、
前記識別子毎に下り波長と上り波長との全ての組み合わせにおけるRTTを記憶するテーブル(不図示)と、
前記テーブルを参照して子ノード200aに割り当てられている下り波長と上り波長の組み合わせに対応するRTTを検出し、前記RTTを考慮して上り信号の送信許容時間を決定して前記子ノードに通知する制御器(不図示)と、
を有する。
それぞれ固有の下り波長と固有の上り波長が設定される複数の光送受信器51と、
各々の光送受信器51と接続され、光送受信器51からの波長の相異なる下り信号を波長多重して光ファイバ伝送路250に出力し、光ファイバ伝送路250からの上り信号を分岐して光送受信器51に結合する光合分波手段151と、
を有しており、
前記制御器は、
ディスカバリ時に、1の光送受信器51に1の下り波長の探索信号を送信させるとともに、いずれかの光送受信器51で受信した未登録の子ノード200aが送信する応答信号を用いてディスカバリを実行する。
親ノード100aが送信した探索信号に応答信号で応答した未登録の子ノード200aに波長変更時に不変である識別子を付与するとともに、
親ノード100aと子ノード200aとの間のRTT及び光ファイバ伝送路250の屈折率の波長依存性を用いて、前記識別子毎に親ノード100aから子ノード200aへの下り信号の下り波長と子ノード200aから親ノード100aへの上り信号の上り波長との全ての組み合わせにおけるRTTを算出するレンジングを行い、前記レンジングで算出した前記全ての組み合わせにおけるRTTを記憶する。
子ノード200aに付与した識別子を波長変更時に不変とし、
前記識別子毎に親ノード100aから子ノード200aへの下り信号の下り波長と子ノード200aから親ノード100aへの上り信号の上り波長との全ての組み合わせにおけるRTTをテーブルに記憶し、
前記テーブルを参照して子ノード200aに割り当てられている下り波長と上り波長の組み合わせに対応するRTTを検出し、前記RTTを考慮して上り信号の送信許容時間を決定して子ノード200aに通知する。
そして、前記全ての組み合わせにおけるRTTを前記ディスカバリ方法で行う前記レンジングで算出する。
図8は、第2の実施形態における光通信システム302である波長可変型WDM/TDM-PONの構成である。光通信システム302は、親ノード100c、子ノード200c、及び光ファイバ伝送路250を備える。
波長λD1~λDMの下り波長が設定可能な複数の光送受信器51と、
各々の光送受信器51が光送受信器側端子を介して接続され、光送受信器51からの前記下り信号を下り波長に応じて異なる光ファイバ伝送路側端子から出力して光ファイバ伝送路250に結合し、前記光ファイバ伝送路側端子に入力された光ファイバ伝送路250からの上り信号を上り波長に応じて異なる前記光送受信器側端子から出力して光送受信器51に結合する波長ルーティング手段152と、
を有しており、
前記制御器は、
ディスカバリ時に、複数の光送受信器51に1の下り波長の探索信号を送信させるとともに、いずれかの光送受信器51で受信した未登録の子ノード200cが送信する応答信号を用いて前記ディスカバリ方法を実行する。
図10は、第3の実施形態における光通信システム302aである波長可変型WDM/TDM-PONの構成である。光通信システム302aは、第2の実施形態の子ノード200cを第1の実施形態の子ノード200aに置換したものである。すなわち、子ノード200aは、受光器21の前段に波長可変フィルタ22を配置し、波長可変フィルタ22の透過波長を割り当てられた下り波長に応じて変化させることにより、所望の波長の下り信号光を選択的に受信する構成である。波長可変フィルタ22を配置することにより、光ファイバ伝送路250中に波長の異なる下り信号光を波長多重して伝送できる。よって、波長ルーティング手段152の同一の光ファイバ伝送路側端子と光ファイバ伝送路250を介して接続された子ノード群の内の異なる子ノードが同時に下り信号光を受信することが可能となる。
本実施形態の光通信システムは、実施形態1で説明した光通信システム(図3~図4、図6)の構成と同じであるが、ディスカバリの際に親ノードがλD1~λDMの全波長で探索信号を送信する。すなわち、親ノード100aは、
波長λD1~λDMの下り波長のうちの少なくとも1波長が設定可能な複数の光送受信器51と、
各々の光送受信器51と接続され、光送受信器51からの波長の相異なる下り信号を波長多重して光ファイバ伝送路250に出力し、光ファイバ伝送路250からの上り信号を分岐して光送受信器51に結合する光合分波手段151と、
を有しており、
前記制御器は、
ディスカバリ時に、少なくとも1の光送受信器51を用いて複数の下り波長の探索信号を送信させるとともに、いずれかの光送受信器51で受信した未登録の子ノード200aが送信する応答信号を用いて前記ディスカバリ方法を実行する。
本実施形態の光通信システムは、実施形態2で説明した光通信システム(図8)または実施形態3で説明した光通信システム(図10)の構成と同じであるが、ディスカバリの際に親ノードがλD1~λDMのうちの全部または複数の波長で探索信号を送信する。すなわち、親ノード100cは、
波長λD1~λDMの下り波長が設定可能な複数の光送受信器51と、
各々の光送受信器51が光送受信器側端子を介して接続され、光送受信器51からの前記下り信号を下り波長に応じて異なる光ファイバ伝送路側端子から出力して光ファイバ伝送路250に結合し、前記光ファイバ伝送路側端子に入力された光ファイバ伝送路250からの上り信号を上り波長に応じて異なる前記光送受信器側端子から出力して光送受信器51に結合する波長ルーティング手段152と、
を有しており、
前記制御器は、
ディスカバリ時に、1の光送受信器51に複数の下り波長の探索信号を送信させるとともに、いずれかの光送受信器51で受信した未登録の子ノード200cが送信する応答信号を用いて前記ディスカバリ方法を実行する。
図14は、第6の実施形態における光通信システムである波長可変型WDM/TDM-PONの構成である。第5の実施形態における波長可変型WDM/TDM-PONの構成との違いは、親ノード内の波長ルーティング手段152の光ファイバ伝送路側端子の数Mが光送受信器側端子の数Hより大きいであることである。波長ルーティング手段152における下り信号光および上り信号光の入出力関係を、それぞれ図20及び図21に示す。第5の実施形態と同様に、各々の子ノード200cには、ディスカバリプロセスを通じて付与されたLLID等の識別子が割当波長の変更によらず固定的に付与され、親ノード100cは、各々の子ノード200cと識別子との対応に加えて、各々の子ノード200cとの間でのフレームのRTTを割当波長の組み合わせ全てについて記録した図17のような管理テーブルを備える。図17では、識別子としてLLIDを用いている。
前記親ノードは、波長λD1~λDM(Mは2以上の整数)である下り信号光を送出し、波長λU1~λUN(Nは2以上の整数)である上り信号光が入力され、
前記子ノードのうち前記親ノードに登録済みの前記子ノードは、λD1~λDM、λU1~λUNから1つずつの波長がそれぞれ下り波長と上り波長として前記親ノードから割り当てられ、割り当てられている前記下り波長と同じ波長である前記下り信号光を受信し、割り当てられている前記上り波長で前記上り信号光を送出する光通信システムにおいて、前記子ノードのうち前記親ノードに未登録である前記子ノードを登録するディスカバリ方法であり、
前記親ノードは、全ての前記子ノードに向けて探索信号を送信し、
前記子ノードのうち前記親ノードに未登録である前記子ノードは、前記探索信号を受信した時に、前記親ノードに向けて応答信号を送信し、
前記親ノードは、前記応答信号を受信した時に、送信元の前記子ノードを子ノードごとに固有の識別子に対応させて登録するとともに、前記探索信号および前記応答信号の送受信に要した時間から、当該の前記子ノードに登録後に割り当てる前記下り波長と前記上り波長の組み合わせ全てについて、当該の前記子ノードとの間でのフレームの往復伝搬時間を記憶することを特徴とするディスカバリ方法。
前記親ノードに未登録である前記子ノードは、前記探索信号を受信可能であることを特徴とする上記(1)または(2)に記載のディスカバリ方法。
前記複数の光送受信器が、光送受信器ごとに固有の波長の信号光を送受信し、
前記光合分波手段151が、各々の前記光送受信器と接続され、前記複数の光送受信器からの波長の相異なる前記下り信号光を波長多重して前記光ファイバ伝送路250に出力する親ノードである前記光通信システムにおいて、
前記光送受信器のうちの1個が前記単一の波長である前記探索信号を送信し、
前記子ノードが送信する前記応答信号は、前記光合分波手段151により分岐された後、前記光送受信器のうちのいずれかで受信されることを特徴とする上記(3)に記載のディスカバリ方法。
前記複数の光送受信器が、波長λD1~λDM/λU1~λUNである信号光を送信/受信可能であり、
前記波長ルーティング手段152が、各々の前記光送受信器と別々の光送受信器側端子を介して接続され、前記複数の光送受信器からの前記下り信号光を波長に応じて異なる光ファイバ伝送路側端子から前記光ファイバ伝送路250に出力する親ノードである前記光通信システムにおいて、
前記光送受信器のうちの全部または複数個が前記単一の波長である前記探索信号を送信し、
前記子ノードが送信する前記応答信号は、前記波長ルーティング手段152により異なる前記光送受信器側端子を介して前記光送受信器のうちのいずれかで受信されることを特徴とする上記(3)に記載のディスカバリ方法。
前記親ノードに未登録である前記子ノードは、前記λD1~λDMのうちの全部または複数の波長のうちの少なくとも1つの波長である前記探索信号を受信可能であることを特徴とする上記(1)または(2)に記載のディスカバリ方法。
前記複数の光送受信器が、光送受信器ごとに固有の波長の信号光を送受信し、
前記光合分波手段151が、各々の前記光送受信器と接続され、前記複数の光送受信器からの波長の相異なる前記下り信号光を波長多重して前記光ファイバ伝送路250に出力する親ノードである前記光通信システムにおいて、
前記光送受信器のうちの少なくとも1個の光送受信器を用いて、波長λD1~λDMの前記探索信号を送信し、
前記探索信号を送信する前記光送受信器の中に、複数波長の前記探索信号を送信する前記光送受信器がある場合には、少なくとも当該光送受信器は送信光波長の変更が可能であり、前記複数波長の前記探索信号を時間多重して送信し、
前記子ノードが送信する前記応答信号は、前記光合分波手段151により分岐された後、前記光送受信器のうちのいずれかで受信されることを特徴とする上記(6)に記載のディスカバリ方法。
前記複数の光送受信器が、波長λD1~λDM/λU1~λUNである信号光を送信/受信可能であり、
前記波長ルーティング手段152が、各々の前記光送受信器と別々の光送受信器側端子を介して接続され、前記複数の光送受信器からの前記下り信号光を波長に応じて異なる光ファイバ伝送路側端子から前記光ファイバ伝送路250に出力する親ノードである前記光通信システムにおいて、
前記光送受信器は、λD1~λDMのうちの全部または複数の波長で前記探索信号を時間多重して送信し、
前記子ノードが送信する前記応答信号は、前記波長ルーティング手段152により波長に応じて異なる前記光送受信器側端子を介して前記光送受信器のうちのいずれかで受信されることを特徴とする上記(6)に記載のディスカバリ方法。
前記親ノードは、波長λD1~λDM(Mは2以上の整数)である下り信号光を送出し、波長λU1~λUN(Nは2以上の整数)である上り信号光が入力され、
前記子ノードは、λD1~λDM、λU1~λUNから1つずつの波長がそれぞれ下り波長と上り波長として前記親ノードから割り当てられ、割り当てられている前記下り波長と同じ波長である前記下り信号光を受信し、割り当てられている前記上り波長で信号光を送出する光通信システムの光通信方法であり、
前記親ノードで、同じ前記上り波長を割り当てられている異なる前記子ノードが送出する前記信号光同士が衝突しないように、各々の前記子ノードに割り当てる前記下り波長と前記上り波長の組み合わせ全てについて記憶している各々の前記子ノードとの間でのフレームの往復伝搬時間を考慮して、前記上り信号光のフレーム長および送信時刻を決定する手順と、
前記親ノードが、前記上り信号光のフレーム長および送信時刻を、前記子ノードに通知する手順と、
前記子ノードで、前記親ノードから通知された前記フレーム長である前記上り信号光を、前記親ノードから通知された前記送信時刻に送出する手順とを行うことを特徴とする光通信方法。
前記親ノードは、波長λD1~λDM(Mは2以上の整数)である下り信号光を送出し、波長λU1~λUN(Nは2以上の整数)である上り信号光が入力され、
前記子ノードは、λD1~λDM、λU1~λUNから1つずつの波長がそれぞれ下り波長と上り波長として前記親ノードから割り当てられ、割り当てられている前記下り波長と同じ波長である前記下り信号光を受信し、割り当てられている前記上り波長で前記上り信号光を送出する光通信システムであり、
各々の前記子ノードには、子ノードごとに固有の識別子が固定的に付与され、
前記親ノードは、各々の前記子ノードと前記識別子との対応に加えて、各々の前記子ノードに割り当てる前記下り波長と前記上り波長の組み合わせ全てについて各々の前記子ノードとの間でのフレームの往復伝搬時間を記録した管理テーブルを備えることを特徴とする光通信システム。
前記親ノードからの通知は、同じ前記上り波長を割り当てられている異なる前記子ノードからの前記上り信号光同士が衝突しないように、前記管理テーブルに記載の前記往復伝搬時間を考慮して、前記親ノードにて決定されることを特徴とする上記(10)に記載の光通信システム。
前記複数の光送受信器が、光送受信器ごとに固有の波長の前記下り信号光を送受信し、
前記光合分波手段151が、各々の前記光送受信器と接続され、前記複数の光送受信器からの波長の相異なる前記下り信号光を波長多重して前記光ファイバ伝送路250に出力し、
前記子ノードが送信する前記上り信号光は、前記光合分波手段151により分岐された後、前記光送受信器のうちのいずれかで受信されることを特徴とする上記(10)または(11)に記載の光通信システム。
前記複数の光送受信器が、波長λD1~λDM/λU1~λUNである信号光を送信/受信可能であり、
前記波長ルーティング手段152が、各々の前記光送受信器と別々の光送受信器側端子を介して接続され、前記複数の光送受信器からの前記下り信号光を波長に応じて異なる光ファイバ伝送路側端子から前記光ファイバ伝送路250に出力する親ノードである前記光通信システムにおいて、
前記子ノードが送信する前記上り信号光は、前記波長ルーティング手段152により波長に応じて異なる前記光送受信器側端子を介して前記光送受信器のうちのいずれかで受信されることを特徴とする上記(10)または(11)に記載の光通信システム。
12:波長合分波手段
13:波長フィルタ
14:受光器
15:光受信器
16:コヒーレント受信器
17:局発光源
18:波長可変光送信器
19:光受信器
21:受光器
22:波長可変フィルタ
23:光受信器
24:波長可変光送信器
26:波長合分波手段
27:コヒーレント受信器
28:局発光源
51:OSU
100a、100b、100c:親ノード
151:光合分波手段
152:波長ルーティング手段
200、200a、200b、200c:子ノード
250:光ファイバ伝送路
300、300a、301、301a、301b、302、302a、302b:光通信システム
Claims (8)
- 親ノードと複数の子ノードとが光ファイバ伝送路で接続される波長可変型WDM/TDM-PON(WDM:Wavelength Division Multiplexing、TDM:Time Division Multiplexing、PON:Passive Optical Network)でのディスカバリ方法であって、
前記親ノードが送信した探索信号に応答信号で応答した未登録の前記子ノードに波長変更時に不変である識別子を付与するとともに、
前記親ノードと前記子ノードとの間の往復伝搬時間(RTT:Round Trip Time)及び前記光ファイバ伝送路の屈折率の波長依存性を用いて、前記識別子毎に前記親ノードから前記子ノードへの下り信号の下り波長と前記子ノードから前記親ノードへの上り信号の上り波長との全ての組み合わせにおけるRTTを算出するレンジングを行い、前記レンジングで算出した前記全ての組み合わせにおけるRTTを記憶することを特徴とするディスカバリ方法。 - 親ノードと複数の子ノードとが光ファイバ伝送路で接続される波長可変型WDM/TDM-PONでの光通信方法であって、
前記子ノードに付与した識別子を波長変更時に不変とし、
前記識別子毎に前記親ノードから前記子ノードへの下り信号の下り波長と前記子ノードから前記親ノードへの上り信号の上り波長との全ての組み合わせにおけるRTTをテーブルに記憶し、
前記テーブルを参照して前記子ノードに割り当てられている下り波長と上り波長の組み合わせに対応するRTTを検出し、前記RTTを考慮して上り信号の送信許容時間を決定して前記子ノードに通知することを特徴とする光通信方法。 - 前記全ての組み合わせにおけるRTTを請求項1に記載のディスカバリ方法で行う前記レンジングで算出することを特徴とする請求項2に記載の光通信方法。
- 波長λD1~λDM(Mは2以上の整数)である下り信号を送出し、波長λU1~λUN(Nは2以上の整数)である上り信号が入力される親ノードと、
それぞれに波長変更時に不変である識別子が付与され、下り波長として波長λD1~λDMのいずれか一つ、上り波長として波長λU1~λUNのいずれか一つが前記親ノードから割り当てられ、割り当てられている下り波長の下り信号を受信し、割り当てられている上り波長で上り信号を送出する複数の子ノードと、
前記親ノードと複数の前記子ノードとを接続する光ファイバ伝送路と、
を備える光通信システムであって、
前記親ノードは、
前記識別子毎に下り波長と上り波長との全ての組み合わせにおけるRTTを記憶するテーブルと、
前記テーブルを参照して前記子ノードに割り当てられている下り波長と上り波長の組み合わせに対応するRTTを検出し、前記RTTを考慮して上り信号の送信許容時間を決定して前記子ノードに通知する制御器と、
を有することを特徴とする光通信システム。 - 前記親ノードは、
それぞれ固有の下り波長と固有の上り波長が設定される複数の光送受信器と、
各々の前記光送受信器と接続され、前記光送受信器からの波長の相異なる下り信号を波長多重して前記光ファイバ伝送路に出力し、前記光ファイバ伝送路からの上り信号を分岐して前記光送受信器に結合する光合分波手段と、
を有しており、
前記制御器は、
ディスカバリ時に、1の前記光送受信器に1の下り波長の探索信号を送信させるとともに、いずれかの前記光送受信器で受信した未登録の前記子ノードが送信する応答信号を用いて請求項1に記載のディスカバリ方法を実行することを特徴とする請求項4に記載の光通信システム。 - 前記親ノードは、
波長λD1~λDMの下り波長が設定可能な複数の光送受信器と、
各々の前記光送受信器が光送受信器側端子を介して接続され、前記光送受信器からの前記下り信号を下り波長に応じて異なる光ファイバ伝送路側端子から出力して前記光ファイバ伝送路に結合し、前記光ファイバ伝送路側端子に入力された前記光ファイバ伝送路から 上り信号を上り波長に応じて異なる前記光送受信器側端子から出力して前記光送受信器に結合する波長ルーティング手段と、
を有しており、
前記制御器は、
ディスカバリ時に、複数の前記光送受信器に1の下り波長の探索信号を送信させるとともに、いずれかの前記光送受信器で受信した未登録の前記子ノードが送信する応答信号を用いて請求項1に記載のディスカバリ方法を実行することを特徴とする請求項4に記載の光通信システム。 - 前記親ノードは、
波長λD1~λDMの下り波長のうちの少なくとも1波長が設定可能な複数の光送受信器と、
各々の前記光送受信器と接続され、前記光送受信器からの波長の相異なる下り信号を波長多重して前記光ファイバ伝送路に出力し、前記光ファイバ伝送路からの上り信号を分岐して前記光送受信器に結合する光合分波手段と、
を有しており、
前記制御器は、
ディスカバリ時に、少なくとも1の前記光送受信器を用いて複数の下り波長の探索信号を送信させるとともに、いずれかの前記光送受信器で受信した未登録の前記子ノードが送信する応答信号を用いて請求項1に記載のディスカバリ方法を実行することを特徴とする請求項4に記載の光通信システム。 - 前記親ノードは、
波長λD1~λDMの下り波長が設定可能な複数の光送受信器と、
各々の前記光送受信器が光送受信器側端子を介して接続され、前記光送受信器からの前記下り信号を下り波長に応じて異なる光ファイバ伝送路側端子から出力して前記光ファイバ伝送路に結合し、前記光ファイバ伝送路側端子に入力された前記光ファイバ伝送路からの上り信号を上り波長に応じて異なる前記光送受信器側端子から出力して前記光送受信器に結合する波長ルーティング手段と、
を有しており、
前記制御器は、
ディスカバリ時に、1の前記光送受信器に複数の下り波長の探索信号を送信させるとともに、いずれかの前記光送受信器で受信した未登録の前記子ノードが送信する応答信号を用いて請求項1に記載のディスカバリ方法を実行することを特徴とする請求項4に記載の光通信システム。
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